#include <iostream>
#include <vector>
#include <unordered_set>
#include <algorithm>
 
void removeAll_unordered( std::vector<int> &a, const std::vector<int> &b )
{
     auto end = std::remove_if( a.begin(), a.end(), 
         [set = std::unordered_set<int>( b.begin(), b.end() )]( int i ) {
     	return set.count( i );
     } );
     a.erase( end, a.end() );
}
 
int main() {
    std::vector<int> a = { 5, 7, 14, 0, 6, 2, 9, 11, 3 };
    std::vector<int> b = { 6, 4, 3, 10, 9, 15, 7 };
    removeAll_unordered( a, b );
    for( auto i : a ) std::cout << i << " ";
    std::cout << std::endl;
	return 0;
}

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